Lubricating composition



Patented Jan. 2, 1945 2,366,517 LUBRICATING comrosrrron Anthony H.Gleason, Westfield, N. J., asslgnor to Standard Oil Development Company,a corporation of Delaware No Drawing. Application March 27, 1943, SerialNo. 480,831 I 8Claims. ((1252-56) This invention relates to lilbricatingoils blendedwith compounds to impart to the composites good viscositycharacteristics. The invention relates particularly to the blending inmineral lubricating oils of new type copolymer products as a means ofpreparing lubricating oil compositions of good viscosity-temperaturecharacteristics.

The lubricating oil industry has been confronted for some time withmeeting the demandsw over, by such blending there are prepared many'highly satisfactory lubricants'in a simple and relatively inexpensivemanner, To this field of development the present invention relates.

Hydrocarbon polymeric materials have been employed for some time asadvantageous lubricatihg oil addition agents. The particular'advantagesof these compounds are that they are relatively selective in improvingthe viscositytemperature relationship Without adversely affecting otherdesirable properties of the mineral oils. Moreover, many of thesepolymeric materials may be prepared from refinery by-products andgreater utilization may be thus efiected of these materials. I

The lubricating oil addition agent of this invention is basically acopolymer product of a styrene compound and an unsaturated ester. Theproducts so obtained are relatively stable materials particularlyeffective in lubricating oils as viscosity index improvingagents. Thesecopolymer compounds possess characteristics not normally obtained by thepolymerization of either of the reactants separately. Thus, "polystyreneeven of relatively low molecular weightis almost completely insoluble inparaflin base oils even though the structure of thispolymer'isessentially linear in character. The unsaturated esters, onthe other hand, are generally characterized by oil-solubility, but avery slow rate of polymerization or none at all. In the case of theunsaturated ester, therefore, considerable difiiculty may be experiencedin obtaining a polymer l activity of styrene is satisfactorily coupledwith the oil solubilizing characteristics of the ester.

The styrene compounds which may be used in addition to styrene'itselfare those having nuclear substituents. It has been found that, ingeneral, styrenes substituted in the alpha or beta positions of themolecule lack the desired degree of polymerizing activity. The nuclearsubstituents are preferably either alkyl or aryl-alkyl groupings butheterocyclic, alkoxy and halogencontaining groups which do not affectadversely substantially the solubility of the resultant copolymer may beadvantageously present. In general, however, the more polar thesubstituent group the greater is usually the; adverse effect upon oilsolubility. The substituents maybe present in any position upon thenucleus in the styrene molecule. The presence of alkyl groups normallyimproves the oil solubility but may have a. slight adverse effect uponthe polymerizing action in the formation of the copolymer com-- pounds.Thus, the presence of alkyl substituents is normally desirable,providingthe polymerizing activity,of thevinyl group is notsubstantialllydiminished. The solubility of the copolymer is ef-' fectedalso by the number of carbon atoms in the alcoholic portion of theester. Thus a very satisfactory product is prepared from styrene and theester of an unsaturated acid and an alweight, for example one of about12 carbon atoms.

,;The unsaturated esters employed as reactants I in the preparation ofthe copolymer product are preferably unsaturated in the acidic portionof the molecule; that is,.they are formed from unsaturated acids. Thealcohol portion of the molecule may be unsaturated, provided theactivity of the double bond is not such as to be reactive in contactwith the styrene compound. Acids from which suitable esters are formedare acrylic, crotonic, methacrylic, maleic, fumaric and cinnamic acids.In order to ensure com plete oil solubility, it is advisable to employesters prepared from the higher alcohols such as octyl, dodecyl, oroctadecyl.

The copolymerization between the styrene compound and the unsaturatedester is eifected at a temperature usually between C. and C. The mixtureis heated for several days in a sealed tube and preferably in thepresence of an organic peroxide such as benzoyl peroxide as a catalyst.The products obtained are dissolved in naphtha o1- benzol andprecipitated therefrom by the addition of a lower alcohol such asethanol. The reaction products usually vary in physical characteristicsfrom being highly vis The dry product w cous liquids to having a'consistency of almost a solid. Analyses of the products indicate thatthe ratio of styrene to ester in the copolymer on a molar basis isconsiderably greater than one.

was obtained in 55% yield which contained 33% by weight of the fumaricester.

The copolymer product is blended in mineral lubricating oils in amountsbetween 0.25% and 7% by weight ofthe oil. In most cases, howi ever, thecopolymer products are blended in the oils in amounts between 0.5% and5% by weight of the oil. In these percentage ranges the copolymerproduct has a substantial blending effeet with mineral oils forimparting to the composite an enhanced viscosity index without adverselyafiectin other desirable properties of the mineral oil, especiallystability under oxidizing conditions and resistance to deteriorationsuch as sludge formation anddevelopment of corrosive tendencies,

As specific illustrationsof the invention, the

following examples are presented:

Example 1 A mass copolymer was prepared by heating a mixture of twovolumes of a p-methyl styrene (57% purity, the impurities consisting ofsaturated aralkyl compounds which were nonreactive) and one volume ofoctyl fumarate with 1% benzoyl peroxide for 72 hours at 110 C.- Thepurified copolymer when blended in lubricating oil presented thefollowing comparison data:

' Vis./100 Via/210 V. 1.

Mineral oil S. A. E. \V+2% copolyxner 7 352.1 52.7 63 Mineral oil S. A.E. 20W alone 275.8 45. 9 13 Example 2 Two parts p-methyl styrene (57%purity as above) and one part of octyl cinnamate were emulsifiedwith sixparts lauryl amine hydrochloride solution (2% pH 5.7) containing 0.1%potassium persulfate and heated for two days at 509 C. On coagulation ofthe resulting latex a copolymer was obtained which possessed the samepotency in raising the Viscosity Index as the product described in theprevious example.

Example 3 About equal volumes of dodecyl maleate and styrene were mixedwith 2% by weig}zit of benzoyl peroxide and the mixture heated in asealed tube for 48 hours at a temperature 'etween 130 C. and 140 C. Thecrude prod ly viscous oil. Purificatio was obtained by dissolving theproduct in enzol and reprecipitating from solution b the additionoimethanol.

substantially a solid. Analysis of the pro uct indicated by weight was aclear, high-- till formed from ,t e dodecyl maleate; that is, a

styrene-este mol ratio of 15 to 1. When dissolved in n S. A. E. 20 oilthe following com- Via/ Via/210 v. 1.

Mineral all s. A. E. 20W 275.8 45.9 13 Mineral oil 8. A. E. 20W+3%ccpolymer 307.3 52.8 70

Example 4 When 3% was dissolved in S. A. E. 20 oil the followingcomparison of data was obtained:

] Vis./l00 i Vis./210 |v.1.

Mineral oil S. A. Mineral oil S. A.

men...

E. 20W+3% copoly- Example 5 Equal volumes of dodecyl methacrylate andstyrene containing a. trace of benzoyl peroxide were heated at C.overnight. The product obtained was dissolved in benzene andrepreclpitated by the addition of isopropanol. Analysis of the productindicated 54% by weight of dodecyl methacrylate; that is, a mol ratio ofstyrene to ester of 3 to 1. When dissolved in an S. A. E. 20 minerallubricating oil the following comparative data were obtained:

1 Via/100 Vis./2l0 I.

Mineral oil S. A. E. 20W 275. 8 45. 0 13 Mineral oil S. A. E. 20W+2%copolymcr 44l 57.3 80

The invention now having been described and. illustrated, what isclaimed is:

1. A lubricating composition comprising a mineral lubricating oil and0.25% to 7.%-of an oil-' soluble copolymer of a styrene and anunsaturated ester.

2. A lubricating composition according to claim. 1 iii which theoil-soluble copolymer is formed from a nuclear substituted styrene.

3. A lubricating composition according to claim 1 in which theunsaturated ester is formed from an unsaturated acid.

4. A lubricating composition according to claim 1 in which theunsaturated ester is formed from an unsaturated acid and an alcoholhaving at least five carbon atoms.

5. A lubricating composition comprising a mineral lubricating oil andbetween 0.5% and 5% by weight of a copolymer of a styrene and an esterformed from an unsaturated acid.

6. A lubricating composition according to claim 5 in which the copolymeris formed from styrene and an ester of methacrylic acid.

7. A lubricating composition according to claim 5 in which the copolymeris formed from styrene and an ester of fumaric acid.

8. A lubricating composition according to claim 5 in which the copolymeris formed from styrene and an ester of cinnamic acid.

ANTHONY H. GLEASON.

